A percentage of a number, one number as a percentage of another, percent change, and adding or subtracting a percentage.
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What do you want to work out?
%
Type two numbers to see the answer — it updates as you type. Nothing you enter leaves your browser.
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100: 25% of 200 is 200 × 25 / 100 = 50. To find what percent A is of B, divide A by B and multiply by 100. The percentage calculator on Tools-Bench does all four everyday percentage sums as you type and shows the formula it used.
About the Percentage Calculator
A percentage is a share of a hundred: 25% means 25 out of every 100. This calculator covers the four sums people most often need — a percentage of a number, one number as a percentage of another, the percentage change between two numbers, and adding or subtracting a percentage — and shows the formula behind each answer, so you can check it or do it again by hand.
Percentage change is measured against the starting value, which is why it isn't symmetric: going from 80 to 100 is a 25% rise, but going back from 100 to 80 is a 20% fall. For the same reason, adding 25% and then subtracting 25% doesn't bring you back to where you started. When the starting value is negative, the change is measured against its size, so a move from −10 to −5 counts as a 50% rise.
Percentage points are something else. When an interest rate goes from 4% to 5%, it has risen by one percentage point — and by 25% of itself. News reports mix the two up often enough that it's worth checking which one is meant.
How to use the calculator
1
Choose what to work out
A percentage of a number, what percent one number is of another, the change from an old value to a new one, or a number plus or minus a percentage.
2
Type the two numbers
Use a decimal point (12.5) — a decimal comma is understood too. Negative numbers are fine: start them with a minus sign.
3
Read the answer and the formula
The answer updates as you type, with the formula it came from underneath, so you can see exactly what was calculated.
Frequently asked questions
How do I work out a percentage increase?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 200 to 250: (250 − 200) / 200 × 100 = 25%. A negative answer is a decrease. Choose % change above to have it worked out, with the difference in absolute terms as well.
How do I add 25% to a price?
Multiply the price by 1.25 — that is, by 1 plus the percentage divided by 100. 200 plus 25% is 200 × 1.25 = 250. To subtract 25%, multiply by 0.75 instead: 200 minus 25% is 150.
How do I find the price before a percentage was added?
Divide by 1 plus the percentage divided by 100. If 250 already includes 25%, the price before it was 250 / 1.25 = 200. Subtracting 25% from 250 gives 187.50 instead, which is wrong: the 25% was worked out on the smaller number.
Why doesn't a 20% rise undo a 20% fall?
Because each percentage is worked out from a different starting value. 100 falls 20% to 80, but 20% of 80 is only 16, so a 20% rise takes it to 96. To get back to 100 from 80, it has to rise by 25%.
What is the difference between percent and percentage points?
Percentage points measure the gap between two percentages; percent measures a change relative to where you started. A rate going from 4% to 5% has risen by 1 percentage point, but by 25% relative to its old level.
Are the numbers I type stored?
No. The calculation happens in your browser as you type, and nothing is sent to a server or stored.